Another thing I wanted to add: I had some success with a filter. I bought this one: Circular Polarizer Lens CPL For DDPai mini2 -
https://www.amazon.com/gp/B075WPDY5N
It fit onto the camera, but there was vignetting on the sides, and I lost a good 5 degrees on both sides. Since the lens rotates, I took two pliers and was able to separate the two pieces (both are metal). When I placed the actual lens section back on the camera, there was still some, though less, vignetting.
Then I tried flipping the lens over and voila! It rested right over, and there was only a tad bit of vignetting in the corners. I watched my phone as I slowly turned the lens to find it's optimal placement (pain in the butt get fingers out of the way, but it works if you're patient. [EDIT] Shoulda used needle-nosed pliers, lol ]) Then I used electrical tape (for now) to hold the lens to the camera, and cut out a square where the recording light is. I'll see how long the tape holds, but I'm definitely getting another one of these for the B1W in my wife's car, too!